framework/main/classes/file_directories/binary/class_BaseBinaryFile.php

   1 <?php
   2 // Own namespace
   3 namespace Org\Mxchange\CoreFramework\Filesystem\File;
   4
   5 // Import framework stuff
   6 use Org\Mxchange\CoreFramework\Factory\ObjectFactory;
   7 use Org\Mxchange\CoreFramework\Filesystem\Block;
   8 use Org\Mxchange\CoreFramework\Filesystem\Block\CalculatableBlock;
   9 use Org\Mxchange\CoreFramework\Filesystem\File\BaseAbstractFile;
  10
  11 // Import SPL stuff
  12 use \SplFileInfo;
  13
  14 /**
  15  * A general binary file class
  16  *
  17  * @author              Roland Haeder <webmaster@ship-simu.org>
  18  * @version             0.0.0
  19 <<<<<<< HEAD:framework/main/classes/file_directories/binary/class_BaseBinaryFile.php
  20  * @copyright   Copyright (c) 2007, 2008 Roland Haeder, 2009 - 2017 Core Developer Team
  21 =======
  22  * @copyright   Copyright (c) 2007, 2008 Roland Haeder, 2009 - 2016 Core Developer Team
  23 >>>>>>> Some updates::inc/main/classes/file_directories/binary/class_BaseBinaryFile.php
  24  * @license             GNU GPL 3.0 or any newer version
  25  * @link                http://www.ship-simu.org
  26  *
  27  * This program is free software: you can redistribute it and/or modify
  28  * it under the terms of the GNU General Public License as published by
  29  * the Free Software Foundation, either version 3 of the License, or
  30  * (at your option) any later version.
  31  *
  32  * This program is distributed in the hope that it will be useful,
  33  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  34  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  35  * GNU General Public License for more details.
  36  *
  37  * You should have received a copy of the GNU General Public License
  38  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  39  */
  40 abstract class BaseBinaryFile extends BaseAbstractFile {
  41         /**
  42          * Separator for header data
  43          */
  44         const SEPARATOR_HEADER_DATA = 0x01;
  45
  46         /**
  47          * Separator header->entries
  48          */
  49         const SEPARATOR_HEADER_ENTRIES = 0x02;
  50
  51         /**
  52          * Separator group->hash
  53          */
  54         const SEPARATOR_GROUP_HASH = 0x03;
  55
  56         /**
  57          * Separator hash->value
  58          */
  59         const SEPARATOR_HASH_VALUE = 0x04;
  60
  61         /**
  62          * Separator entry->entry
  63          */
  64         const SEPARATOR_ENTRIES = 0x05;
  65
  66         /**
  67          * Separator type->position
  68          */
  69         const SEPARATOR_TYPE_POSITION = 0x06;
  70
  71         /**
  72          * Length of count
  73          */
  74         const LENGTH_COUNT = 20;
  75
  76         /**
  77          * Length of position
  78          */
  79         const LENGTH_POSITION = 20;
  80
  81         /**
  82          * Length of group
  83          */
  84         const LENGTH_GROUP = 10;
  85
  86         /**
  87          * Maximum length of entry type
  88          */
  89         const LENGTH_TYPE = 20;
  90
  91         //***** Array elements for 'gaps' array *****
  92
  93         /**
  94          * Start of gap
  95          */
  96         const GAPS_INDEX_START = 'start';
  97
  98         /**
  99          * End of gap
 100          */
 101         const GAPS_INDEX_END = 'end';
 102
 103         /**
 104          * Current seek position
 105          */
 106         private $seekPosition = 0;
 107
 108         /**
 109          * Size of header
 110          */
 111         private $headerSize = 0;
 112
 113         /**
 114          * File header
 115          */
 116         private $header = array();
 117
 118         /**
 119          * Seek positions for gaps ("fragmentation")
 120          */
 121         private $gaps = array();
 122
 123         /**
 124          * Seek positions for damaged entries (e.g. mismatching hash sum, ...)
 125          */
 126         private $damagedEntries = array();
 127
 128         /**
 129          * Back-buffer
 130          */
 131         private $backBuffer = '';
 132
 133         /**
 134          * Currently loaded block (will be returned by current())
 135          */
 136         private $currentBlock = '';
 137
 138         /**
 139          * Protected constructor
 140          *
 141          * @param       $className      Name of the class
 142          * @return      void
 143          */
 144         protected function __construct ($className) {
 145                 // Call parent constructor
 146                 parent::__construct($className);
 147
 148                 // Init counters and gaps array
 149                 $this->initCountersGapsArray();
 150         }
 151
 152         /**
 153          * Checks whether the abstracted file only contains gaps by counting all
 154          * gaps' bytes together and compare it to total length.
 155          *
 156          * @return      $isGapsOnly             Whether the abstracted file only contains gaps
 157          */
 158         private function isFileOnlyGaps () {
 159                 // First/last gap found?
 160                 /* Only for debugging
 161                 if (isset($this->gaps[0])) {
 162                         // Output first and last gap
 163                         self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] this->gaps[0]=%s,this->gaps[%s]=%s', __METHOD__, __LINE__, print_r($this->gaps[0], true), (count($this->gaps) - 1), print_r($this->gaps[count($this->gaps) - 1], true)));
 164                 } // END - if
 165                 */
 166
 167                 // Now count every gap
 168                 $gapsSize = 0;
 169                 foreach ($this->gaps as $gap) {
 170                         // Calculate size of found gap: end-start including both
 171                         $gapsSize += ($gap[self::GAPS_INDEX_END] - $gap[self::GAPS_INDEX_START]);
 172                 } // END - if
 173
 174                 // Debug output
 175                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] gapsSize=%s,this->headerSize=%s', __METHOD__, __LINE__, $gapsSize, $this->getHeaderSize()));
 176
 177                 // Total gap size + header size must be same as file size
 178                 $isGapsOnly = (($this->getHeaderSize() + $gapsSize) == $this->getFileSize());
 179
 180                 // Return status
 181                 return $isGapsOnly;
 182         }
 183
 184         /**
 185          * Initializes counter for valid entries, arrays for damaged entries and
 186          * an array for gap seek positions. If you call this method on your own,
 187          * please re-analyze the file structure. So you are better to call
 188          * analyzeFile() instead of this method.
 189          *
 190          * @return      void
 191          */
 192         public function initCountersGapsArray () {
 193                 // Init counter and seek position
 194                 $this->setCounter(0);
 195                 $this->setSeekPosition(0);
 196
 197                 // Init arrays
 198                 $this->gaps = array();
 199                 $this->damagedEntries = array();
 200         }
 201
 202         /**
 203          * Getter for header size
 204          *
 205          * @return      $totalEntries   Size of file header
 206          */
 207         public final function getHeaderSize () {
 208                 // Get it
 209                 return $this->headerSize;
 210         }
 211
 212         /**
 213          * Setter for header size
 214          *
 215          * @param       $headerSize             Size of file header
 216          * @return      void
 217          */
 218         public final function setHeaderSize ($headerSize) {
 219                 // Set it
 220                 $this->headerSize = $headerSize;
 221         }
 222
 223         /**
 224          * Getter for header array
 225          *
 226          * @return      $totalEntries   Size of file header
 227          */
 228         public final function getHeader () {
 229                 // Get it
 230                 return $this->header;
 231         }
 232
 233         /**
 234          * Setter for header
 235          *
 236          * @param       $header         Array for a file header
 237          * @return      void
 238          */
 239         public final function setHeader (array $header) {
 240                 // Set it
 241                 $this->header = $header;
 242         }
 243
 244         /**
 245          * Getter for seek position
 246          *
 247          * @return      $seekPosition   Current seek position (stored here in object)
 248          */
 249         public final function getSeekPosition () {
 250                 // Get it
 251                 return $this->seekPosition;
 252         }
 253
 254         /**
 255          * Setter for seek position
 256          *
 257          * @param       $seekPosition   Current seek position (stored here in object)
 258          * @return      void
 259          */
 260         protected final function setSeekPosition ($seekPosition) {
 261                 // And set it
 262                 $this->seekPosition = $seekPosition;
 263         }
 264
 265         /**
 266          * Updates seekPosition attribute from file to avoid to much access on file.
 267          *
 268          * @return      void
 269          */
 270         public function updateSeekPosition () {
 271                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 272
 273                 // Get key (= seek position)
 274                 $seekPosition = $this->key();
 275                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] Setting seekPosition=%s', __METHOD__, __LINE__, $seekPosition));
 276
 277                 // And set it here
 278                 $this->setSeekPosition($seekPosition);
 279
 280                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 281         }
 282
 283         /**
 284          * Seeks to beginning of file, updates seek position in this object and
 285          * flushes the header.
 286          *
 287          * @return      void
 288          */
 289         protected function rewindUpdateSeekPosition () {
 290                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 291
 292                 // flushFileHeader must be callable
 293                 assert(is_callable(array($this, 'flushFileHeader')));
 294
 295                 // Seek to beginning of file
 296                 $this->rewind();
 297
 298                 // And update seek position ...
 299                 $this->updateSeekPosition();
 300
 301                 // ... to write it back into the file
 302                 $this->flushFileHeader();
 303
 304                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 305         }
 306
 307         /**
 308          * Seeks to old position
 309          *
 310          * @return      void
 311          */
 312         protected function seekToOldPosition () {
 313                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 314
 315                 // Seek to currently ("old") saved position
 316                 $this->seek($this->getSeekPosition());
 317
 318                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 319         }
 320
 321         /**
 322          * Checks whether the block separator has been found
 323          *
 324          * @param       $str            String to look in
 325          * @return      $isFound        Whether the block separator has been found
 326          */
 327         public static function isBlockSeparatorFound ($str) {
 328                 // Determine it
 329                 $isFound = (strpos($str, chr(self::SEPARATOR_ENTRIES)) !== false);
 330
 331                 // Return result
 332                 return $isFound;
 333         }
 334
 335         /**
 336          * Initializes the back-buffer by setting it to an empty string.
 337          *
 338          * @return      void
 339          */
 340         private function initBackBuffer () {
 341                 // Simply call the setter
 342                 $this->setBackBuffer('');
 343         }
 344
 345         /**
 346          * Setter for backBuffer field
 347          *
 348          * @param       $backBuffer             Characters to "store" in back-buffer
 349          * @return      void
 350          */
 351         private function setBackBuffer ($backBuffer) {
 352                 // Cast to string (so no arrays or objects)
 353                 $backBuffer = (string) $backBuffer;
 354
 355                 // ... and set it
 356                 $this->backBuffer = $backBuffer;
 357         }
 358
 359         /**
 360          * Getter for backBuffer field
 361          *
 362          * @return      $backBuffer             Characters "stored" in back-buffer
 363          */
 364         private function getBackBuffer () {
 365                 return $this->backBuffer;
 366         }
 367
 368         /**
 369          * Setter for currentBlock field
 370          *
 371          * @param       $currentBlock           Characters to set a currently loaded block
 372          * @return      void
 373          */
 374         private function setCurrentBlock ($currentBlock) {
 375                 // Cast to string (so no arrays or objects)
 376                 $currentBlock = (string) $currentBlock;
 377
 378                 // ... and set it
 379                 $this->currentBlock = $currentBlock;
 380         }
 381
 382         /**
 383          * Gets currently read data
 384          *
 385          * @return      $current        Currently read data
 386          */
 387         public function getCurrentBlock () {
 388                 // Return it
 389                 return $this->currentBlock;
 390         }
 391
 392         /**
 393          * Initializes this file class
 394          *
 395          * @param       $infoInstance   An instance of a SplFileInfo class
 396          * @return      void
 397          */
 398         protected function initFile (SplFileInfo $infoInstance) {
 399                 // Get a file i/o pointer instance
 400                 $pointerInstance = ObjectFactory::createObjectByConfiguredName('file_raw_input_output_class', array($infoInstance));
 401
 402                 // ... and set it here
 403                 $this->setPointerInstance($pointerInstance);
 404         }
 405
 406         /**
 407          * Writes data at given position
 408          *
 409          * @param       $seekPosition   Seek position
 410          * @param       $data                   Data to be written
 411          * @param       $flushHeader    Whether to flush the header (default: flush)
 412          * @return      void
 413          */
 414         public function writeData ($seekPosition, $data, $flushHeader = true) {
 415                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] seekPosition=%s,data()=%d - CALLED!', __METHOD__, __LINE__, $seekPosition, strlen($data)));
 416
 417                 // Write data at given position
 418                 $this->getPointerInstance()->writeAtPosition($seekPosition, $data);
 419
 420                 // Increment counter
 421                 $this->incrementCounter();
 422
 423                 // Update seek position
 424                 $this->updateSeekPosition();
 425
 426                 // Flush the header?
 427                 if ($flushHeader === true) {
 428                         // Flush header
 429                         $this->flushFileHeader();
 430
 431                         // Seek to old position
 432                         $this->seekToOldPosition();
 433                 } // END - if
 434
 435                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 436         }
 437
 438         /**
 439          * Marks the currently loaded block as empty (with length of the block)
 440          *
 441          * @param       $length         Length of the block
 442          * @return      void
 443          */
 444         protected function markCurrentBlockAsEmpty ($length) {
 445                 // Get current seek position
 446                 $currentPosition = $this->key();
 447
 448                 // Now add it as gap entry
 449                 array_push($this->gaps, array(
 450                         self::GAPS_INDEX_START  => ($currentPosition - $length),
 451                         self::GAPS_INDEX_END    => $currentPosition,
 452                 ));
 453         }
 454
 455         /**
 456          * Checks whether the file header is initialized
 457          *
 458          * @return      $isInitialized  Whether the file header is initialized
 459          */
 460         public function isFileHeaderInitialized () {
 461                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 462
 463                 // Default is not initialized
 464                 $isInitialized = false;
 465
 466                 // Is the file initialized?
 467                 if ($this->isFileInitialized()) {
 468                         // Some bytes has been written, so rewind to start of it.
 469                         $rewindStatus = $this->rewind();
 470                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] rewindStatus=%s', __METHOD__, __LINE__, $rewindStatus));
 471
 472                         // Is the rewind() call successfull?
 473                         if ($rewindStatus != 1) {
 474                                 // Something bad happened
 475                                 self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] Could not rewind().', __METHOD__, __LINE__));
 476                         } // END - if
 477
 478                         // Read file header
 479                         $this->readFileHeader();
 480
 481                         // The above method does already check the header
 482                         $isInitialized = true;
 483                 } // END - if
 484
 485                 // Return result
 486                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] isInitialized=%d - EXIT!', __METHOD__, __LINE__, intval($isInitialized)));
 487                 return $isInitialized;
 488         }
 489
 490         /**
 491          * Checks whether the assigned file has been initialized
 492          *
 493          * @return      $isInitialized          Whether the file's size is zero
 494          */
 495         public function isFileInitialized () {
 496                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 497
 498                 // Get it from iterator which holds the pointer instance. If false is returned
 499                 $fileSize = $this->size();
 500                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] fileSize=%s', __METHOD__, __LINE__, $fileSize));
 501
 502                 /*
 503                  * The returned file size should not be false or NULL as this means
 504                  * that the pointer class does not work correctly.
 505                  */
 506                 assert(is_int($fileSize));
 507
 508                 // Is more than 0 returned?
 509                 $isInitialized = ($fileSize > 0);
 510
 511                 // Return result
 512                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] isInitialized=%d - EXIT!', __METHOD__, __LINE__, intval($isInitialized)));
 513                 return $isInitialized;
 514         }
 515
 516         /**
 517          * Creates the assigned file
 518          *
 519          * @return      void
 520          */
 521         public function createFileHeader () {
 522                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 523
 524                 // The file's header should not be initialized here
 525                 assert(!$this->isFileHeaderInitialized());
 526
 527                 // Simple flush file header which will create it.
 528                 $this->flushFileHeader();
 529
 530                 // Rewind seek position (to beginning of file) and update/flush file header
 531                 $this->rewindUpdateSeekPosition();
 532
 533                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 534         }
 535
 536         /**
 537          * Pre-allocates file (if enabled) with some space for later faster write access.
 538          *
 539          * @param       $type   Type of the file
 540          * @return      void
 541          */
 542         public function preAllocateFile ($type) {
 543                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 544
 545                 // Is it enabled?
 546                 if ($this->getConfigInstance()->getConfigEntry($type . '_pre_allocate_enabled') != 'Y') {
 547                         // Not enabled
 548                         self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] Not pre-allocating file.', __METHOD__, __LINE__));
 549
 550                         // Don't continue here.
 551                         return;
 552                 } // END - if
 553
 554                 // Message to user
 555                 self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] Pre-allocating file ...', __METHOD__, __LINE__));
 556
 557                 // Calculate minimum length for one entry
 558                 $minLengthEntry = $this->getBlockInstance()->calculateMinimumBlockLength();
 559                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] minLengthEntry=%s', __METHOD__, __LINE__, $minLengthEntry));
 560
 561                 // Calulcate seek position
 562                 $seekPosition = $minLengthEntry * $this->getConfigInstance()->getConfigEntry($type . '_pre_allocate_count');
 563                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] seekPosition=%s', __METHOD__, __LINE__, $seekPosition));
 564
 565                 // Now simply write a NUL there. This will pre-allocate the file.
 566                 $this->writeData($seekPosition, chr(0));
 567
 568                 // Rewind seek position (to beginning of file) and update/flush file header
 569                 $this->rewindUpdateSeekPosition();
 570
 571                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 572         }
 573
 574         /**
 575          * Determines seek position
 576          *
 577          * @return      $seekPosition   Current seek position
 578          */
 579         public function determineSeekPosition () {
 580                 // Call pointer instance
 581                 return $this->getPointerInstance()->determineSeekPosition();
 582         }
 583
 584         /**
 585          * Seek to given offset (default) or other possibilities as fseek() gives.
 586          *
 587          * @param       $offset         Offset to seek to (or used as "base" for other seeks)
 588          * @param       $whence         Added to offset (default: only use offset to seek to)
 589          * @return      $status         Status of file seek: 0 = success, -1 = failed
 590          */
 591         public function seek ($offset, $whence = SEEK_SET) {
 592                 // Call pointer instance
 593                 return $this->getPointerInstance()->seek($offset, $whence);
 594         }
 595
 596         /**
 597          * Reads given amount of bytes from file.
 598          *
 599          * @param       $bytes  Amount of bytes to read
 600          * @return      $data   Data read from file
 601          */
 602         public function read ($bytes = NULL) {
 603                 // $bytes shall be integer
 604                 assert(is_int($bytes));
 605
 606                 // Call pointer instance
 607                 return $this->getPointerInstance()->read($bytes);
 608         }
 609
 610         /**
 611          * Rewinds to the beginning of the file
 612          *
 613          * @return      $status         Status of this operation
 614          */
 615         public function rewind () {
 616                 // Call pointer instance
 617                 return $this->getPointerInstance()->rewind();
 618         }
 619
 620         /**
 621          * Analyzes entries in index file. This will count all found (and valid)
 622          * entries, mark invalid as damaged and count gaps ("fragmentation"). If
 623          * only gaps are found, the file is considered as "virgin" (no entries).
 624          *
 625          * @return      void
 626          */
 627         public function analyzeFile () {
 628                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 629
 630                 // Make sure the file is initialized
 631                 assert($this->isFileInitialized());
 632
 633                 // Init counters and gaps array
 634                 $this->initCountersGapsArray();
 635
 636                 // Output message (as this may take some time)
 637                 self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] Analyzing file structure ... (this may take some time)', __METHOD__, __LINE__));
 638
 639                 // First rewind to the begining
 640                 $this->rewind();
 641
 642                 // Then try to load all entries
 643                 while ($this->valid()) {
 644                         // Go to next entry
 645                         $this->next();
 646
 647                         // Get current entry
 648                         $current = $this->getCurrentBlock();
 649
 650                         /*
 651                          * If the block is empty, maybe the whole file is? This could mean
 652                          * that the file has been pre-allocated.
 653                          */
 654                         if (empty($current)) {
 655                                 // Then skip this part
 656                                 continue;
 657                         } // END - if
 658
 659                         // Debug message
 660                         /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] current()=%d', __METHOD__, __LINE__, strlen($current)));
 661                 } // END - while
 662
 663                 // If the last read block is empty, check gaps
 664                 if (empty($current)) {
 665                         // Output message
 666                         self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] Found a total of %s gaps.', __METHOD__, __LINE__, count($this->gaps)));
 667
 668                         // Check gaps, if the whole file is empty.
 669                         if ($this->isFileOnlyGaps()) {
 670                                 // Only gaps, so don't continue here.
 671                                 return;
 672                         } // END - if
 673
 674                         /*
 675                          * The above call has calculated a total size of all gaps. If the
 676                          * percentage of gaps passes a "soft" limit and last
 677                          * defragmentation is to far in the past, or if a "hard" limit has
 678                          * reached, run defragmentation.
 679                          */
 680                         if ($this->isDefragmentationNeeded()) {
 681                                 // Run "defragmentation"
 682                                 $this->doRunDefragmentation();
 683                         } // END - if
 684                 } // END - if
 685                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 686         }
 687
 688         /**
 689          * Advances to next "block" of bytes
 690          *
 691          * @return      void
 692          */
 693         public function next () {
 694                 // Is there nothing to read?
 695                 if (!$this->valid()) {
 696                         // Nothing to read
 697                         return;
 698                 } // END - if
 699
 700                 // Debug message
 701                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d] key()=%d', __FUNCTION__, __LINE__, $this->key()));
 702
 703                 // Make sure the block instance is set
 704                 assert($this->getBlockInstance() instanceof CalculatableBlock);
 705
 706                 // First calculate minimum block length
 707                 $length = $this->getBlockInstance()->calculateMinimumBlockLength();
 708                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d] length=%s', __FUNCTION__, __LINE__, $length));
 709
 710                 // Short be more than zero!
 711                 assert($length > 0);
 712
 713                 // Read possibly back-buffered bytes from previous call of next().
 714                 $data = $this->getBackBuffer();
 715
 716                 /*
 717                  * Read until a entry/block separator has been found. The next read
 718                  * "block" may not fit, so this loop will continue until the EOB or EOF
 719                  * has been reached whatever comes first.
 720                  */
 721                 while ((!$this->isEndOfFileReached()) && (!self::isBlockSeparatorFound($data))) {
 722                         // Then read the next possible block
 723                         $block = $this->read($length);
 724
 725                         // Debug message
 726                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d] block()=%d,length=%s', __FUNCTION__, __LINE__, strlen($block), $length));
 727
 728                         // Is it all empty?
 729                         if (strlen(trim($block)) == 0) {
 730                                 // Mark this block as empty
 731                                 $this->markCurrentBlockAsEmpty(strlen($block));
 732
 733                                 // Skip to next block
 734                                 continue;
 735                         } // END - if
 736
 737                         // At this block then
 738                         $data .= $block;
 739
 740                         // A debug message
 741                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput(sprintf('[%s:%d] data()=%d', __FUNCTION__, __LINE__, strlen($data)));
 742                 } // END - while
 743
 744                 // EOF reached?
 745                 if ($this->isEndOfFileReached()) {
 746                         // Set whole data as current read block
 747                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('Calling setCurrentBlock(' . strlen($data) . ') ...');
 748                         $this->setCurrentBlock($data);
 749
 750                         // Then abort here silently
 751                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('EOF reached.');
 752                         return;
 753                 } // END - if
 754
 755                 /*
 756                  * Init back-buffer which is the data that has been found beyond the
 757                  * separator.
 758                  */
 759                 $this->initBackBuffer();
 760
 761                 // Separate data
 762                 $dataArray = explode(chr(self::SEPARATOR_ENTRIES), $data);
 763
 764                 // This array must contain two elements
 765                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__, __LINE__)->debugOutput('dataArray=' . print_r($dataArray, true));
 766                 assert(count($dataArray) == 2);
 767
 768                 // Left part is the actual block, right one the back-buffer data
 769                 $this->setCurrentBlock($dataArray[0]);
 770                 $this->setBackBuffer($dataArray[1]);
 771         }
 772
 773         /**
 774          * Checks wether the current entry is valid (not at the end of the file).
 775          * This method will return true if an emptied (nulled) entry has been found.
 776          *
 777          * @return      $isValid        Whether the next entry is valid
 778          */
 779         public function valid () {
 780                 // Make sure the block instance is set
 781                 assert($this->getBlockInstance() instanceof Block);
 782
 783                 // First calculate minimum block length
 784                 $length = $this->getBlockInstance()->calculateMinimumBlockLength();
 785
 786                 // Short be more than zero!
 787                 assert($length > 0);
 788
 789                 // Get current seek position
 790                 $seekPosition = $this->key();
 791
 792                 // Then try to read it
 793                 $data = $this->read($length);
 794
 795                 // If some bytes could be read, all is fine
 796                 $isValid = ((is_string($data)) && (strlen($data) > 0));
 797
 798                 // Get header size
 799                 $headerSize = $this->getHeaderSize();
 800
 801                 // Is the seek position at or beyond the header?
 802                 if ($seekPosition >= $headerSize) {
 803                         // Seek back to old position
 804                         $this->seek($seekPosition);
 805                 } else {
 806                         // Seek directly behind the header
 807                         $this->seek($headerSize);
 808                 }
 809
 810                 // Return result
 811                 return $isValid;
 812         }
 813
 814         /**
 815          * Gets current seek position ("key").
 816          *
 817          * @return      $key    Current key in iteration
 818          */
 819         public function key () {
 820                 // Call pointer instance
 821                 return $this->getPointerInstance()->determineSeekPosition();
 822         }
 823
 824         /**
 825          * Reads the file header
 826          *
 827          * @return      void
 828          */
 829         public function readFileHeader () {
 830                 // Make sure the block instance is set
 831                 assert($this->getBlockInstance() instanceof Block);
 832
 833                 // Call block instance
 834                 $this->getBlockInstance()->readFileHeader();
 835         }
 836
 837         /**
 838          * Flushes the file header
 839          *
 840          * @return      void
 841          */
 842         public function flushFileHeader () {
 843                 // Make sure the block instance is set
 844                 assert($this->getBlockInstance() instanceof Block);
 845
 846                 // Call block instance
 847                 $this->getBlockInstance()->flushFileHeader();
 848         }
 849
 850         /**
 851          * Searches for next suitable gap the given length of data can fit in
 852          * including padding bytes.
 853          *
 854          * @param       $length                 Length of raw data
 855          * @return      $seekPosition   Found next gap's seek position
 856          */
 857         public function searchNextGap ($length) {
 858                 // If the file is only gaps, no need to seek
 859                 if ($this->isFileOnlyGaps()) {
 860                         // The first empty block is the first one right after the header
 861                         return ($this->getHeaderSize() + 1);
 862                 } // END - if
 863
 864                 // @TODO Unfinished
 865                 $this->partialStub('length=' . $length);
 866         }
 867
 868 }